1. Field of the Invention
The present invention relates to a display device wherein a plurality of plasma tube array-type display sub-modules is joined to one another, thereby constructing a large-screen, more particularly to a display device capable of preventing the occurrence of a low brightness at a joining portion between the plurality of plasma tube array-type display sub-modules joined to one another.
2. Description of the Related Art
As a technology for realizing a next-generation large-screen display device, a plasma tube array-type display sub-module has been developed with a structure that a plurality of plasma tubes each filled with a discharge gas is arranged in parallel. For example, a large-screen display device having a scale of several meters by several meters in size can be constructed of a plasma tube array-type display system module that a plurality of plasma tube array-type display sub-modules of one square-meter in size is joined to one another. The display device of such a type that the plurality of plasma tube array-type display sub-modules is joined to one another does not need either a large glass substrate to be handled, like an LCD, a PDP and the like, nor a large-scale facility and achieves uniform image quality at low cost.
However, in case where the plurality of plasma tube array-type display sub-modules is joined horizontally to one another, the position adjustment of these modules requires a high precision in order to maintain a high quality of an image in a single plasma tube array-type display system module. A non-luminescent region is easily generated, particularly at the joining portion between the adjacent plasma tube array-type display sub-modules joined to one another, and a brightness is low in the region comparing to the other regions. Therefore, such a problem as black thin lines in an image easily occurs at the joining portion.
A technology for manufacturing a large-screen display device arranged a plurality of small display panels in parallel is disclosed in the JP 2003-150083 A, for example, which is a display device wherein the position of the display panels is position-adjusted and then secured by a positioning member so that distances between pixel arrays of the adjacent display panels can be equal. According to the display device wherein the distances between the pixel arrays, comprising the distance between the pixel arrays at the joining portion, are all equal, it can be avoided that the brightness in a particular region is lower than that in the other regions, which prevents the generation of the black thin lines in the image.
The invention disclosed in JP 2003-150083 A, however, has disadvantages in that it is not possible to equalize the clearance between the adjacent pixel arrays of the display panel and the clearance between the adjacent pixel arrays of the adjacent display panels unless a step of attaching the positioning member is separately provided, which results in the increase of manufacturing steps. Meanwhile, in the case where the plasma tube array-type display sub-modules are joined horizontally to one another, terminal portions of the display electrodes are bent toward the back side space along an outermost plasma tube at the side edges of the plasma tube array-type display sub-modules for electrical connection. Therefore, a certain gap width is occurred between the adjacent plasma tube array-type display sub-modules.